Quote:
Originally Posted by SiriusHardware
Yes, it's been suggested before that the MH devices could actually be programmed using the hardware method and algorithm for the SN (Texas) prefix devices - only trouble is, Texas don't ever seem to have made an SN74S571 so it's not as though you can just choose 'Texas / SN74S571' on your 'western' programmer to programme MH74S571s.
Texas did make a SN74S287, and here is an article about programming those - the author points out what may be a critical difference between the SN and MH devices (roughly 8th paragraph down) so they may not be as directly programmer-compatible as it first seems.
http://randomvariations.com/2014/09/...87-programmer/ |
Yes, it seems TI were relatively late to Bipolar PROMs (Maybe busy keeping up with Intel on EPROM's), and they never made some of the larger ones.
Although it seems National Semi weren't there first either, with it actually being Harris (Even though they don't seem to be as widely used as others, as well as not as many programmers supporting these):
http://www.bitsavers.org/components/...is_Bipolar.pdf
"Harris introduced the industry's first bipolar programmable read only memory (PROM) in 1970, and has continued as a leader in the field of bipolar
PROMs. Harris offers a complete spectrum of bipolar PROMs from 256 bits
to 64K bits. In 1982, Harris became the first supplier of a new family of programmable logic (HPL) featuring patented on-chip testability"
So I wonder if all makes of Bipolar PROM do have on-chip Testability, that National mention in their later DM74S571 datasheet.
Most manufacturers have cross-reference guides with comprehensive list of other manufacturer's types. But they all seem to not mention anything about programming compatibility.
I recall seeing that randomvariations webpage before, where it does seem to indicate that Tesla devices are like National ones in one respect that the bits are all at 0 unless programmed, whereas, TI types appear to start out at 1 (like EPROM's). I know National and some other makes do start out at 0, from ones I've checked, but can't recall what Tesla ones were when I once programmed a couple and haven't current got access to that programmer to check. But I do see that you had said that Tesla ones had been confirmed as also starting with bits at 0, in post 17, here:
https://www.vintage-radio.net/forum/...d.php?t=146388
I've had a play on my older Dataman-48XP programmer , to see what it thinks the blank state should be for the PROM's it supports (Lots of AMD 27S and Philips/Signetics 82S types + a few National DM74S and a couple of TI TBP + Harris HM-66xx ones - Although no MMI or Tesla ones at all).
And all have the blank state as 0, including the TI TBP18S (4bit?) types.
However, the TI TBP28(L/P/S)(2/4)2 8bit ones have blank state of 1 (like it seems the SN74Sxxx ones are)
Strangely the ELNEC-designed Dataman-48Pro range, which supports the Tesla ones, amongst many others, only supported two Phiips/Signetics 82S10(0/1) types)
I have just found this webpage on fusible link proms, with a manual-switches type (I presume you can't over-programme a fuse!) programmer schematic for Signetics ones, and some info - that basically says you need to check specific datasheets for each make (but not really anything about 74S571):
https://www.retrotechnology.com/rest...prom.html#data
Attached are about the most comprehensive data I could find on MH74Sxxx ones' the 'net, with some of it from Tesla's website. And looks to contain the programming info that Slothie had attached a translated version of.